The present invention relates to the field of maintenance machines that apply oil or other dressing to the surface of bowling lanes and, more particularly, to improvements in the manner in which the dressing is supplied to applicator wicks used in such machines.
It is known in the prior art that wick-type lane maintenance machines, wherein wicks are used to absorb lane oil from a reservoir and apply it to a transfer roller or other applicator, perform best when the oil within the reservoir is maintained at a substantially constant, predetermined level. If the oil level is allowed to decrease significantly, the rate of oil transferred by the wick will drop, which makes it difficult to apply an identical oil pattern to all lanes of a bowling establishment. In prior U.S. Pat. No. 5,650,012 assigned to the assignee of the present invention, the oil level within the wick reservoir is maintained substantially constant by continuously pumping oil from a supply tank into the wick reservoir and having it overflow and return back to the supply tank. Thus, the oil level is maintained at the level of the overflow outlet.
In one alternative embodiment disclosed in the ""012 patent, the oil from the pump flows first into a small chamber immediately upstream from the wick reservoir that is in constant communication with the wick reservoir. The overflow outlet remains located in the wick reservoir and overflowing oil is returned back to the main supply tank.
In accordance with the present invention a lane maintenance machine that uses absorbant wicks as part of the dressing application system of the machine automatically maintains dressing at a substantially constant level in the wick reservoir without the use of a pump or overflow system as found in the prior art. The present invention relies solely upon gravity to feed makeup dressing to the wick reservoir if and when such dressing is necessary to maintain the predetermined, optimum level of dressing in the reservoir. A float switch functions to determine whether the level is below the set point and, if so, it signals a controller or otherwise causes a control valve to open a supply conduit from an elevated main tank so that makeup dressing can flow by gravity into the reservoir. In a preferred embodiment of the invention, a relatively small pilot chamber upstream from the wick reservoir but in open communication therewith is placed at such a height that the fluid level in the pilot chamber and the wick reservoir are always the same. Thus, the level of fluid in the wick reservoir can be indirectly controlled by controlling the fluid level in the pilot chamber. To this end, the float sensor is located within the pilot chamber, rather than in the wick reservoir. Constant opening and closing of the float switch as it seeks to maintain a constant fluid level is prevented by having a relatively long stretch of supply conduit between the control valve and the pilot chamber so that, even after the float switch has been deactuated by the fluid level returning to its set point, the volume of fluid in the supply conduit downstream from the pilot valve overfills the control chamber to a certain extent above the set point.